Tunnel boring for TTC subway extension is 90 percent complete

Tunnel boring of four tunnels that are part of theToronto-York Spadina Subway Extension (TYSSE) in Toronto, ON, Canada has reached 90 percent completion.

Toronto Transit Commission (TTC) has two sets of tunnel boring machines (TBMs), Yorkie, Torkie, Holey and Moley, building the north and south tunnels of the TYSSE.

TBMs Holey and Moley have completed boring the southern tunnels of the extension. Holey began work in the summer of 2011 and bored 2.8 kilometers (1.73 miles) of tunnel, placing 1,826 rings before reaching the extraction shaft in December 2012. Moley began work in fall 2011 building the south tunnel adjacent to the one Holey was boring. Moley reached the extraction shaft in March 2013 having bored 1.2 kilometers (.74 miles) and placed 799 rings.

TTC says TBMs Yorkie and Torkie are making great headway on the north tunnels and it expects the machines arrival at the extraction shaft before the end of 2013. Yorkie began the first northern tunnel drive in December 2011 with Torkie starting work in February 2012. The TBMs have completed 1.7 kilometers (1.05 miles) of twin tunnel.

The TYSSE will provide a 8.6-km (5.34-mile) extension for the existing TTC subway system across the municipal boundary between the city of Toronto and The Regional Municipality of York. This will be the first TTC rapid transit line to cross the city of Toronto boundary and service is expected to begin in the fall of 2016.